Polymerizable amino acid compounds and their production

ABSTRACT

A polymerizable amino acid compound of the formula:   &lt;IMAGE&gt; wherein R1, R2 and R3 are each hydrogen or methyl, R4 is C1-C20 alkyl optionally bearing at least one hydroxyl and optionally having -O- or -COO- in the alkyl chain, R5 is hydrogen or C1-C20 alkyl optionally bearing at least one hydroxyl and optionally having -O- or -COO- in the alkyl chain, or when R4 and R5 are taken together with the nitrogen atom to which they are attached, they represent a nitrogen atom containing heterocyclic group, R6 is an alkylene group having not more than 6 carbon atoms and A is -COO- or -SO3-, provided that when R4 is C1-C20 alkyl, R5 is not hydrogen, which is highly soluble in water or organic solvents without any acidic or basic substance and can be introduced into the molecule of high molecular compounds.

This is a division of Ser. No. 372,729 now U.S. 4,452,746, filed Apr.28, 1982 which is a continuation in part of Ser. No. 253,143, filed Apr.10, 1981, now abandoned.

The present invention relates to polymerizable amino acid compounds andtheir production. More particularly, it relates to polymerizable aminoacid compounds which can be introduced into the molecule of highmolecular compounds so as to modify their physical and chemicalproperties, and their production.

When an ionic functional group is introduced into a high molecularcompound, the physical and chemical properties of the high molecularcompound are greatly modified even if the introduced amount of the ionicfunctional group is small. Further, the characteristic properties of anionic functional group are emphasized when the ionic functional group isintroduced into a high molecular compound. Because of these reasons, thestudy on high molecular compounds having ionic functional groups hasbeen highly developed. An interest towards polymerizable monomers havingan inner salt structure and their introduction into high molecularcompounds for enhancing advantageously the reactivity, surface activity,electrochemical properties, biological properties, etc. is particularlyincreased. For instance, Japanese Patent Publication (examined) No.11651/1967. discloses the compound of the formula: ##STR2## Further, forinstance, U.S. Pat. No. 2,840,603 discloses the compounds of theformula:

    CH.sub.2 ═CH--C.sub.6 H.sub.4 --CH(NH.sub.2)--CO.sub.2 M

wherein M is a cation such as hydrogen, ammonium or metal.

In general, ampho-ionic compounds are known to show a lower solubilityat an isoelectric point. Accordingly, it is necessary to enhance theirsolubility by the use of an acidic or basic substance for employing themin the form of solution. However, the use of such acidic or basicsubstance produces the following problems:

(1) When an acidic or basic substance is added to enhance the solubilityof an ampho-ionic compound, the opposite pH condition can not be adoptedso that the separation of the zwitter monomer sometimes takes place andthe polymerization therewith hardly proceeds. Further, the scopes of theinitiator and other additives to be usable on the polymerization arequite restricted.

(2) The polymer composition obtained by polymerization in the presenceof an acidic or basic substance has more or less a tendency to lower thedispersibility of a pigment therein and reduce the performances of acoating film formed thereon in comparison with the polymer compositionobtained by polymerization in the absence of an acidic or basicsubstance.

The main object of the present invention is to provide novel compoundswhich have an inner salt structure and are soluble in water, organicsolvents or liquid monomers, etc. and also which are usable aspolymerizable monomers imparting their characteristic properties to highmolecular compounds.

The novel compounds which are suitable for the said object and can beprovided by this invention are polymerizable amino acid compounds havingan ionic functional group and a carboxylic or sulfonic acid residue aswell as a polymerizable C--C double bond. Such polymerizable amino acidcompounds are representable by the formula: ##STR3## wherein R₁, R₂ andR₃ are each hydrogen or methyl, R₄ is C₁ -C₂₀ and alkyl optionallybearing at least one hydroxyl and optionally having --O-- or --COO-- inthe alkyl chain, R₅ is hydrogen or C₁ -C₂₀ alkyl optionally bearing atleast one hydroxyl and optionally having --O-- or --COO-- in the alkylchain, or when R₄ and R₅ are taken together with the nitrogen atom towhich they are attached, they represent a nitrogen atom containingheterocyclic group, R₆ is an alkylen group having not more than 6 carbonatoms and A is --COO-- or --SO₃ --, provided that when R₄ is C₁ -C₂₀alkyl, R₅ is not hydrogen. The group of --C₆ H₄ -- represents a benzenering throughout the specification.

The polymerizable amino acid compound (I) can be produced by reacting abenzyl halide compound with an amino acid compound. The reaction ispreferably carried out under a basic condition. A typical procedurecomprises reacting a benzyl halide compound with an amino acid compoundin the presence of a basic substance (e.g. alkali metal hydroxides,alkali metal alkoxides, ammonia, organic amines) in a solvent such asalcohols, ethylene glycol monoalkyl ethers, dimethylformamide,dimethylsulfoxide or water, or their mixtures at a temperature of 0° to150° C. under an atmospheric or elevated pressure for a period of 10minutes to 48 hours, usually while stirring.

As the benzyl halide compound, there may be employed the onerepresentable by the formula: ##STR4## wherein X is chlorine or bromineand R₁, R₂ and R₃ are each as defined above. Specific examples arevinylbenzyl chloride, vinylbenzyl bromide, isopropenylbenzyl chloride,isopropenylbenzyl bromide, etc. Among them, the most usually availableis vinylbenzyl chloride. Commercially, they are available as a mixtureof isomers on the benzene ring such as a mixture of m- and p-isomers andmay be as such employed as the starting material without separation intoeach isomer. The resulting product in such case is also a mixture ofisomers on the benzene ring.

As the amino acid compound, there may be employed the one representableby the formula: ##STR5## wherein R₄, R₅, R₆ and A are each as definedabove. Specific examples are N,N-dimethylglycine, N,N-diethylglycine,N-methyl-N-dodecylglycine, N,N-dimethylalanine, N,N-diethylalanine,N-methyl-N-dodecylalanine, N,N-dimethyl-β-alanine,N,N-diethyl-β-alanine, N-methyl-N-dodecyl-β-alanine,N,N-dimethyl-ε-aminocaproic acid, N,N-diethyl-ε-aminocaproic acid,N-methyl-N-dodecyl-ε-aminocaproic acid, N,N-dimethyltaurine,N,N-diethyltaurine, N-methyl-N-dodecyltaurine,N-carboxymethyl-pyrrolidone, N-carboxymethyl-piperidine,N-carboxymethyl-morpholine, N-(1-carboxyethyl)-pyrrolidone,N-(1-carboxyethyl)-piperidine, N-(1-carboxyethyl)-morpholine,N-(2-carboxyethyl)-pyrrolidone, N-(2-carboxyethyl)-piperidineN-(2-carboxyethyl)-morpholine, N-(5-carboxypentyl)-pyrrolidone,N-(5-carboxypentyl)-piperidine, N-(5-carboxypentyl)-morpholine,2-pyrrolidinoethane-suulfonic acid-(1), 2-piperidinoethane-sulfonicacid-(1), 2-morpholinoethane-sulfonic acid-(1), N-hydroxymethylglycine,N-hydroxyethylglycine, N,N-bis(hydroxyethyl)glycine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]-ethylglycine,N-hydroxyethyl-N-dodecylglycine, N-hydroxymethylalanine,N-hydroxyethylalanine, N,N-bis(hydroxyethyl)]alanine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethylalanine,N-hydroxyethyl-N-dodecylalanine, N-hydroxymethyl-β-alanine,N-hydroxyethyl-β-alanine, N,N-bis(hydroxyethyl)-β-alanine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-β-alanine,N-hydroxyethyl-N-dodecyl-β-alanine, N-hydroxymethyl-ε-aminohexanoicacid, N-hydroxyethyl-ε-aminohexanoic acid,N,N-bis(hydroxyethyl)-ε-aminohexanoic acid,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-ε-aminohexanoic acid,N-hydroxyethyl-N-dodecyl-ε-aminohexanoic acid, N-hydroxymethyltaurine,N-hydroxyethyltaurine, N,N-bis(hydroxyethyl)taurine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyltaurine,N-hydroxyethyl-N-dodecyltaurine, etc.

Among these amino acid compounds, those of the formula: ##STR6## whereinR₇ is hydrogen or methyl and R₄ and R₅ are each as defined above may beproduced by reacting an amine of the formula: ##STR7## wherein R₄ and R₅are each as defined above with a sulfonic salt of the formula: ##STR8##wherein M is an alkali metal and R₇ is as defined above, followed bytreatment for elimination of the alkali metal.

Alternatively, the polymerizable amino acid compound (I) may be producedby reacting a benzylamine compound of the formula: ##STR9## wherein R₁,R₂, R₃, R₄ and R₅ are each as defined above with a haloacid or its esterof the formula:

    X--R.sub.6 --A--R.sub.8                                    (V)

wherein R₈ is hydrogen or a C₁ -C₁₂ hydrocarbon group, and R₆, X and Aare each as defined above, optionally followed by hydrolysis in thepresence of an alkaline catalyst. The main reaction may be carried outat a temperature of 0° to 150° C. under an ordinary or elevated pressurefor a period of 10 minutes to 100 hours in the presence or absence of asolvent such as hydrocarbons, esters, ketones, alcohols, ethers, amides,nitriles or sulfoxides, and their mixtures usually while stirring. Thesubsequent hydrolysis may be effected in a per se conventionalprocedure.

Examples of the benzylamine compound (IV) areN,N-dimethyl-(vinylbenzyl)amine, N,N-dimethyl-(isopropenylbenzyl)amine,N,N-diethyl-(vinylbenzyl)amine, N,N-diethyl(isopropenylbenzyl)amine,N,N-dioctyl-(vinylbenzyl)amine, N,N-dioctyl-(isopropenylbenzyl)amine,N-methyl-N-ethyl(vinylbenzyl)amine,N-methyl-N-ethyl-(isopropenylbenzyl)amine,N-methyl-N-dodecyl-(vinylbenzyl)amine,N-methyl-N-dodecyl(isopropenylbenzyl)amine,N-hydroxymethyl-(vinylbenzyl)amine,N-hydroxymethyl-(isopropenylbenzyl)amine,N-hydroxymethyl(vinylbenzyl)amine,N-hydroxyethyl-(isopropenylbenzyl)amine,N,N-bis(hydroxyethyl)-(vinylbenzyl)amine,N,N-bis(hydroxyethyl)-(isopropenylbenzyl)amine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]-ethyl-N-(vinylbenzyl)amine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)amine,N-hydroxyethyl-N-(vinylbenzyl)dodecylamine, etc.

Examples of the haloacid or its esters (V) are chloroacetic acid,bromoacetic acid, ethyl chloroacetate, 2-chloropropionic acid,2-bromopropionic acid, 5-chloro-ε-caproic acid, 5-bromo-ε-caproic acid,etc.

Alternatively, the polymerizable amino acid compound of the formula:##STR10## wherein R₉ is hydrogen or methyl and R₁, R₂, R₃, R₄, R₅ and Aare each as defined above may be produced by reacting the benzylaminecompound (IV) with an α,β-unsaturated acid or its ester of the formula:##STR11## wherein R₁₀ is hydrogen or a C₁ -C₁₂ hydrocarbon group,optionally followed by hydrolysis of the addition product in thepresence of an alkaline catalyst. The main reaction, i.e. addition, maybe carried out, if necessary, in the presence of a solvent such asalcohols, ethylene glycol monoalkyl ethers, dimethylformamide,dimethylsulfoxide or water, or their mixture at a temperature of 0° to150° C. under an atmospheric or elevated pressure for a period of 10minutes to 48 hours. Examples of the α,β-unsaturated acid or its ester(VI) are vinylsulfonic acid, vinylcarboxylic acid, methylvinylsulfonate, ethyl vinylsulfonate, n-butyl vinylsulfonate,2-ethylhexyl vinylsulfonate, dodecyl vinylsulfonate, methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate,butyl methacrylate, dodecyl acrylate, dodecyl methacrylate, etc. In thecase using the α,β-unsaturated acid (VI), it may be subjected to thereaction in its salt form such as alkali metal salt, ammonium salt ororganic amine salt.

Examples of the produced polymerizable amino acid compound (I) areN,N-dimethyl-N-(vinylbenzyl)ammonioacetic acid betaine,N,N-dimethyl-N-(isopropenylbenzyl)ammonioacetic acid betaine,N,N-diethyl-N-(vinylbenzyl)ammonioacetic acid betaine,N,N-diethyl-N-(isopropenylbenzyl)-ammonioacetic acid betaine,N,N-octyl-N-(vinylbenzyl)-ammonioacetic acid betaine,N,N-dioctyl-N-(isopropenylbenzyl)-ammonioacetic acid betaine,N-methyl-N-dodecyl-N-(vinylbenzyl)ammonioacetic acid betaine,N-methyl-N-dodecyl-N-(isopropenylbenzyl)ammonioacetic acid betaine,N,N-dimethyl-N-(vinylbenzyl)ammoniopropionic acid-1 betaine,N-N-dimethyl-N-(isopropenylbenzyl)ammoniopropionic acid-1betaine,N,N-diethyl-N-(vinylbenzyl)ammoniopropionic acid-1 betaine,N,N-diethyl-N-(isopropenylbenzyl)ammniopropionic acid-1 betaine,N,N-dioctyl-N-(vinylbenzyl)ammoniopropionic acid-1 betaine,N,N-dioctyl-N-(isopropenylbenzyl)ammoniopropionic acid-1 betaine,N-methyl-N-dodecyl-N-dodecyl-N-(vinylbenzyl)ammoniopropionic acid-1betaine, N-methyl-N-dodecyl-N-(isopropenylbenzyl)-ammoniopropionicacid-1 betaine, N,N-dimethyl-N-(vinylbenzyl)ammoniopropionic acid-2betaine, N,N-dimethyl-N-(isopropenylbenzyl)ammoniopropionic acid-2betaine, N,N-diethyl-N-(vinylbenzyl)ammonioacetic acid betaine,N,N-diethyl-N-(isopropenylbenzyl)ammoniopropionic acid-2 betaine,N,N-dioctyl-N-(vinylbenzyl)ammoniopropionic acid-2 betaine,N,N-dioctyl-N-(isopropenylbenzyl)ammoniopropionic acid-2 betaine,N-methyl-N-dodecyl-N-(vinylbenzyl)ammoniopropionic acid-2 betaine,N-methyl-N-dodecyl-N-(isopropenylbenzyl)ammoniopropionic acid-2 betaine,N,N-dimethyl-N-(vinylbenzyl)-ammoniocaproic acid-5 betaine,N,N-dimethyl-N-(isopropenylbenzyl)ammoniocaproic acid-5 betaine,N,N-diethyl-N-(vinylbenzyl)ammoniocaproic acid-5 betaine,N,N-diethyl-N-(isopropenylbenzyl)ammoniocaproic acid-5 betaine,N,N-dioctyl-N-(vinylbenzyl)ammoniocaproic acid-5 betaine,N,N-dioctyl-N-(isopropenylbenzyl)ammoniocaproic acid-5 betaine,N-methyl-N-dodecyl-N-(vinylbenzyl)ammoniocaproic acid-5 betaine,N-methyl-N-dodecyl-N-(isopropenylbenzyl)ammoniocaproic acid-5 betaine,N,N-dimethyl-N-(vinylbenzyl)ammonioethanesulfonic acid-2 betaine,N,N-dimethyl-N-(isopropenylbenzyl)ammonioethanesulfonic acid-2 betaine,N,N-diethyl-N-(vinylbenzyl)-ammonioethanesulfonic acid-2 betaine,N,N-diethyl-N-(isopropenylbenzyl)ammonioethanesulfonic acid-2 betaine,N,N-dioctyl-N-(vinylbenzyl)ammonioethanesulfonic acid-2 betaine,N,N-dioctyl-N-(isopropenylbenzyl)ammonioethanesulfonic acid-2 betaine,N-methyl-N-dodecyl-N-(vinylbenzyl)ammonioethanesulfonic acid-2 betaine,N-methyl-N-dodecyl-N-(isopropenylbenzyl)ammonioethanesulfonic acid-2betaine, N-hydroxymethyl-N-(vinylbenzyl)glycine,N-hydroxymethyl-N-(isopropenylbenzyl)-glycine,N-hydroxyethyl-N-(vinylbenzyl)glycine,N-hydroxyethyl-N-(isopropenylbenzyl)glycine,N,N-bis(hydroxyethyl)-N-(vinylbenzyl)ammonioacetic acid betaine,N,N-bis(hydroxyethyl)-N-(isopropenylbenzyl)ammonioacetic acid betaine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(vinylbenzyl)-glycine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)glycine,N-hydroxyethyl-N-dodecyl-N-(vinylbenzyl)ammonioacetic acid betaine,N-hydroxyethyl-N-dodecyl-N-(isopropenylbenzyl)ammonioacetic acidbetaine, N-hydroxymethyl-N-(vinylbenzyl)alanine,N-hydroxymethyl-N-(isopropenylbenzyl)alanine,N-hydroxyethyl-N-(vinylbenzyl)alanine,N-hydroxyethyl-N-(isopropenylbenzyl)alanine,N,N-bis(hydroxyethyl)-N-(vinylbenzyl)ammoniopropionic acid-1 betaine,N,N-bis(hydroxyethyl)-N-(isopropenylbenzyl)ammoniopropionic acid-1betaine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(vinylbenzyl)alanine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]-ethyl-N-(isopropenylbenzyl)alanine,N-hydroxyethyl-N-dodecyl-N-(vinylbenzyl)ammoniopropionic acid-1 betaine,N-hydroxyethyl-N-dodecyl-N-(isopropenylbenzyl)ammoniopropionic acid-1betaine, N-hydroxymethyl-N-(vinylbenzyl)-β-alanine,N-hydroxymethyl-N-(isopropenylbenzyl)-β-analine,N-hydroxyethyl-N-(vinylbenzyl)-β-alanine,N-hydroxyethyl-N-(isopropenylbenzyl)-β-alanine,N,N-bis(hydroxyethyl)-N-(vinylbenzyl)ammoniopropionic acid-2 betaine,N,N-bis(hydroxyethyl)-N-(isopropenylbenzyl)ammoniopropionic acid-2betaine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(vinylbenzyl)-β-alanine,N-]2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)-β-alanine,N-hydroxyethyl-N-dodecyl-N-(vinylbenzyl)ammoniopropionic acid-2 betaine,N-hydroxyethyl-N-dodecyl-N-(isopropenylbenzyl)ammoniopropionic acid-2betaine, N-hydroxymethyl-N-(vinylbenzyl)-ε-aminohexanoic acid,N-hydroxymethyl-N-(isopropenylbenzyl)-ε-aminohexanoic acid,N-hydroxyethyl-N-(vinylbenzyl)-ε-aminohexanoic acid,N-hydroxyethyl-N-(isopropenylbenzyl)-ε-aminohexanoic acid,N,N-bis(hydroxyethyl)-N-(vinylbenzyl)ammoniocaproic acid-5 betaine,N,N-bis(hydroxyethyl)-N-(isopropenylbenzyl)ammoniocaproic acid-5betaine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]-ethyl-N-(vinylbenzyl)-ε-aminohexanoicacid,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)-ε-aminohexanoicacid, N-hydroxyethyl-N-dodecyl-N-(vinylbenzyl)ammoniocaproic acid-5betaine, N-hydroxyethyl-N-dodecyl-N-(isopropenylbenzyl)ammoniocaproicacid-5 betaine, N-hydroxymethyl-N-(vinylbenzyl)taurine,N-hydroxymethyl-N-(isopropenylbenzyl)taurine,N-hydroxyethyl-N-(vinylbenzyl)taurine,N-hydroxyethyl-N-(isopropenylbenzyl)taurine,N,N-bis(hydroxyethyl)-N-(vinylbenzyl)ammonioethanesulfonic acid-2betaine,N,N-bis(hydroxyethyl)-N-(isopropenylbenzyl)ammonioethanesulfonic acid-2betaine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]-ethyl-N-(vinylbenzyl)taurine,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)taurine,N-hydroxyethyl-N-dodecyl-N-(vinylbenzyl)ammonioethanesulfonic acid-2betaine,N-hydroxyethyl-N-dodecyl-N-(isopropenylbenzyl)ammonioethanesulfonicacid-2 betaine, etc.

The polymerizable amino acid compounds (I) have advantageous reactivity,surface activity, electro-chemical properties, biological properties,etc. They are highly soluble in water or organic solvents without anyacidic or basic substance and can be introduced into high molecularsubstances with imparting zwitter characteristics thereto. Particularly,the polymerizable amino acid compounds (I) wherein the acidic grouprepresented by the symbol A is a sulfonium group behave as stronglyacidic inner salt compounds. When the polymerizable amino acid compounds(I) are copolymerized with other polymerizable monomers, there can beobtained resins for dispersing pigments therein. Such copolymerizationmay be carried out by per se conventional polymerization procedures suchas radical polymerization, radiation polymerization, cationicpolymerization and anionic polymerization. Examples of the otherpolymerizable monomers are acrylic monomers, styrenic monomers,conjugated diene monomers, vinyl acetate, ethylene, propylene, vinylchloride, etc.

Practical and presently preferred embodiments of the present inventionare illustratively shown in the following Examples wherein part(s) areby weight.

EXAMPLE 1

Into a 2 liter volume flask equipped with a stirrer, a thermometer and acooler, N,N-dimethyl-(vinylbenzl)amine (161 parts), dimethylformamide(700 parts) and ethyl chloroacetate (122 parts) are charged, and theresultant mixture is heated at 60° C. under stirring. Triethylamine (101parts) is dropwise added thereto, and stirring is continued at 70° C.for 2 hours. After separation of triethylamine hydrochloride asprecipitated by filtration, the mother liquor is added to a solution ofsodium hydroxide (40 parts) in water (300 parts) at 100° C. forhydrolysis. The reaction mixture is neutralized with hydrochloric acid,and acetone is added thereto. The precipitated substance is collected byfiltration and dried under reduced pressure to give a white solidmaterial (203 parts), of which the NMR chart is as shown in FIG. 1 ofthe accompanying drawings. Thus, the product is identified to beN,N-dimethyl-N-(vinylbenzyl)ammonioacetic acid betaine of the formula:##STR12##

EXAMPLE 2

Into the same flask as in Example 1, N,N-diethyl-ε-aminocaproic acid(182 parts), sodium hydroxide (40 parts), deionized water (300 parts)and ethylene glycol monoethyl ether (150 parts) are charged, and theresultant mixture is heated at 80° C. under stirring. A mixture ofvinylbenzyl chloride (153 parts) and ethylene glycol monoethyl ether(100 parts) is dropwise added thereto in 2 hours, during which sodiumhydroxide (each 20 parts) is added thereto 1 hour and 2 hours after thestart of the dropwise addition. Stirring under heating is furthercontinued for 10 hours. The reaction mixture is neutralized withhydrochloric acid, and acetone is added thereto to precipitate a whitesolid substance. The white solid substance is collected by filtrationand dried under reduced pressure to giveN,N-diethyl-N-(vinylbenzyl)ammoniocaproic acid-5 betaine (238 parts) ofthe formula: ##STR13## of which the NMR chart is shown in FIG. 2.

EXAMPLE 3

Into the same flask as in Example 1, N,N-dimethyltaurine (153 parts),ethylene glycol (250 parts), sodium ethylate (68 parts) and ethyleneglycol monomethyl ether (100 parts) are charged, and the resultantmixture is heated to 100° C. under stirring. A mixture of vinylbenzylchloride (153 parts) and ethylene glycol monomethyl ether (100 parts) isdropwise added thereto in 2 hours, and stirring is continued for 5hours. Acetone is added to the reaction mixture to precipitate a whitesolid substance. The substance is collected by filtration and driedunder reduced pressure to giveN,N-dimethyl-N-(vinylbenzyl)ammonioethanesulfonic acid-2 betaine (220parts) of the formula: ##STR14## of which the NMR chart is shown in FIG.3.

EXAMPLE 4

In the same manner as in Example 3 but using N,N-di-n-butyl-β-alanine inplace of N,N-dimethyltaurine, the reaction is carried out to giveN,N-di-n-butyl-N-(vinylbenzyl)ammoniopropionic acid-2 betaine (256parts) of the formula: ##STR15## of which the NMR chart is shown in FIG.4.

EXAMPLE 5

In the same manner as in Example 3 but using N,N-diethyltaurine (181parts), the reaction is carried out to giveN,N-diethyl-N-(vinylbenzyl)ammonioethanesulfonic acid-2 betaine (242parts) of the formula: ##STR16## of which the NMR chart is shown in FIG.5.

EXAMPLE 6

In the same manner as in Example 3 but using N-(2-sulfoethyl)morpholine(195 parts), the reaction is carried out to giveN-(vinylbenzyl)morpholinoethanesulfonic acid-2 betaine (250 parts) ofthe formula: ##STR17## of which the NMR chart is shown in FIG. 6.

EXAMPLE 7

In the same manner as in Example 3 but usingN-methyl-N-(n-dodecyl)taurine (277 parts), the reaction is carried outto give N-methyl-N-(n-dodecyl)-N-(vinylbenzyl)-ammonioethanesulfonicacid-2 betaine (312 parts) of the formula: ##STR18## of which the NMRchart is shown in FIG. 7.

Reference Examples

Solubilities of the compounds obtained in Examples 1 to 7 in water at20° C. or 80° C. or in methanol at 30° C. are shown in Table 1 in termsof amount (g) of the compound soluble in 100 g of solvent. Forcomparison, solubilities of N-(vinylbenzyl)glycine (Comparative Example1), N-(vinylbenzyl)-β-alanine (Comparative Example 2),N-(vinylbenzyl)-taurine (Comparative Example 3) andN-methyl-N-(vinylbenzyl)-taurine (Comparative Example 4) in the samesolvents are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                 Solubility in Solubility in                                                   water (g)     methanol (g)                                           Compound   20° C.                                                                            80° C.                                                                          30° C.                                  ______________________________________                                        Example                                                                       1          >100       >100     1-20                                           2           20-100    >100     20-100                                         3          >100       >100     1-20                                           4           20-100    >100     20-100                                         5          >100       >100     1-20                                           6          >100       >100     20-100                                         7           1-20       20-100  1-20                                           Comparative                                                                   Example                                                                       1          0-1        0-1      0-1                                            2          0-1        0-1      0-1                                            3          0-1        0-1      0-1                                            4          0-1        0-1      0-1                                            ______________________________________                                    

EXAMPLE 8

In the same flask as in Example 1,N-(2-hydroxyethyl)-N-octyl-ε-aminohexanoic acid (287 parts), water (300parts), ethylene glycol monomethyl ether (200 parts) and sodiumhydroxide (40 parts) are charged, and the resultant mixture is heated to80° C. under stirring. After a homogeneous solution is attained, amixture of vinylbenzyl chloride (153 parts) and ethylene glycolmonomethyl ether (100 parts) is dropwise added thereto in 2 hours,during which sodium hydroxide (each 20 parts) is added thereto 1 hourand 2 hours after start of the dropwise addition. Stirring under heatingis further continued for 6 hours. The reaction mixture is neutralizedwith dilute hydrochloric acid and acetone is added thereto toprecipitate a white honey-like substance. The precipitated substance isdissolved in warm water and cooled. Then acetone is added thereto toreprecipitate the substance, which is dried under reduced pressure togive a white viscous material (304 parts). By NMR analysis, the materialis identified to beN-(2-hydroxyethyl)-N-octyl-N-(vinylbenzyl)ammoniocaproic acid-5 betaineof the formula: ##STR19##

EXAMPLE 9

Into the same flask as in Example 1,N-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)amine(251 parts), dimethylformaldehyde (1000 parts) and ethyl chloroacetate(125 parts) are charged, and the resultant mixture is heated at 60° C.under stirring. Triethylamine (101 parts) is dropwise added thereto, andstirring is continued at 70° C. for 2 hours. After separation oftriethylamine hydrochloride as precipitated by filtration, the motherliquor is added to a solution of sodium hydroxide (40 parts) in water(300 parts) at 100° C. for hydrolysis. The reaction mixture isneutralized with hydrochloric acid, and acetone is added thereto toprecipitate a substance, which is collected by filtration and driedunder reduced pressure to give a white solid material (310 parts). ByNMR, elementary analyses and measurement of molecular weight, theproduct is identified to beN-[2-hydroxy-1,1-bis(hydroxymethyl)]ethyl-N-(isopropenylbenzyl)glycineof the formula: ##STR20##

EXAMPLE 10

Into the same flask as in Example 1, N-(2-hydroxyethyl)-β-alanine (117parts), sodium ethylate (68 parts), ethylene glycol (300 parts) andethylene glycol monomethyl ether (150 parts) are charged, and theresultant mixture is heated at 100° C. under stirring. A mixture ofvinylbenzyl chloride (152 parts) and ethylene glycol monomethyl ether(100 parts) is dropwise added thereto in 2 hours. Stirring under heatingis further continued for 6 hours. The reaction mixture is neutralizedwith hydrochloric acid, and acetone is added thereto to precipitate awhite solid substance. The white solid substance is collected byfiltration and dried under reduced pressure to giveN-(2-hydroxyethyl)-N-(vinylbenzyl)-β-alanine (191 parts) of the formula:##STR21## of which the NMR chart is shown in FIG. 8.

EXAMPLE 11

In the same flask as in Example 1, (hydroxyethyl)-(vinylbenzyl)amine(177 parts) and ethyl acrylate (100 parts) are charged, and theresultant mixture is heated at 80° C. for 3 hours while stirring. Afteraddition of deionized water (200 parts) and sodium hydroxide (40 parts),the reaction mixture is subjected to hydrolysis at 100° C., followed byneutralization with hydrochloric acid. The precipitate is collected byfiltration and dried under reduced pressure to give a white solidmaterial (204 parts), of which the structure is identical with that ofExample 10.

EXAMPLE 12

In the same manner as in Example 10 but usingN,N-bis(2-hydroxyethyl)-β-alanine (161 parts) in place ofN-(2-hydroxyethyl)-β-alanine, the reaction is carried out to giveN,N-bis(2-hydroxyethyl)-N-(vinylbenzyl)ammoniopropionic acid-2 betaine(220 parts) of the formula: ##STR22## of which the NMR chart is shown inFIG. 9.

EXAMPLE 13

In the same manner as in Example 10 but using N-(2-hydroxyethyl)glycine(103 parts), the reaction is carried out to giveN-(2-hydroxyethyl)-N-(vinylbenzyl)glycine (180 parts) of the formula:##STR23## of which the NMR chart is shown in FIG. 10.

EXAMPLE 14

In the same manner as in Example 10 but using N-(2-hydroxyethyl)taurine(169 parts), the reaction is carried out to giveN-(2-hydroxyethyl)-N-(vinylbenzyl)taurine (229 parts) of the formula:##STR24## of which the NMR chart is shown in FIG. 11.

EXAMPLE 15

In the same manner as in Example 10 but usingN,N-bis(2-hydroxyethyl)taurine (203 parts), the reaction is carried outto give N,N-bis(2-hydroxyethyl)-N-(vinylbenzyl)-ammonioethanesulfonicacid-2 betaine (263 parts) of the formula: ##STR25## of which the NMRchart is shown in FIG. 12.

EXAMPLE 16

In the same manner as in Example 10 but usingN-(2-hydroxydodecyl)taurine (309 parts), the reaction is carried out togive N-(2-hydroxydodecyl)-N-(vinylbenzyl)-taurine (327 parts) of theformula: ##STR26##

EXAMPLE 17

In the same manner as in Example 10 but usingN-methyl-N-(2-hydroxyethyl)taurine (183 parts), the reaction is carriedout to giveN-methyl-N-(2-hydroxyethyl)-N-(vinylbenzyl)ammonioethanesulfonic acid-2betaine (245 parts) of the formula: ##STR27## of which the NMR chart isshown in FIG. 13.

Reference Examples

Solubilities of the compounds obtained in Examples 8 to 17 in water at20° C. or 80° C. are shown in Table 2 in terms of amount (g) of thecompound soluble in 100 g of water. For comparison, solubilities ofN-(vinylbenzyl)-glycine (Comparative Example 5),N-(vinylbenzyl)-β-alanine (Comparative Example 6),N-(vinylbenzyl)taurine (Comparative Example 7) andN-methyl-N-(vinylbenzyl)taurine (Comparative Example 8) in water areshown in Table 2.

    ______________________________________                                                        Solubility in water (g)                                       Compound          20° C.                                                                           80° C.                                     ______________________________________                                        Example                                                                        8                1         10                                                 9                4         60                                                10                1         20                                                11                1         20                                                12                2         30                                                13                2         30                                                14                1         20                                                15                2         25                                                16                1         10                                                17                6         100                                               Comparative Example                                                           5                 0         <1                                                6                 0         <1                                                7                 0         <1                                                8                 0         <1                                                ______________________________________                                    

What is claimed is:
 1. A process for preparing a polymerizable amino acid compound of the formula: ##STR28## wherein R₁, R₂ and R₃ are each hydrogen or methyl, R₄ is C₁ -C₂₀ alkyl optionally substituted with at least one hydroxyl and optionally substituted with --O-- or --COO-- in the alkyl chain, R₅ is hydrogen or C₁ -C₂₀ alkyl optionally substituted with at least one hydroxyl and with or without --O-- or --COO-- in the alkyl chain, R₆ is an alkylene group having not more than 6 carbon atoms and A is --COO-- or --SO₃ --, provided that when R₄ is C₁ -C₂₀ alkyl, R₅ is not hydrogen which comprises reacting a benzyl halide of the formula: ##STR29## wherein X is chlorine or bromine and R₁, R₂ and R₃ are each as defined above with an amino acid compound of the formula: ##STR30## wherein R₄, R₅, R₆ and A are each defined above under basic conditions at a temperature of 0° to 150° C. in the absence or presence of a solvent.
 2. The process according to claim 1, wherein the solvent is alcohol, ethylene glycol monoalkyl ether, dimethylformamide, dimethylsulfoxide or water, or a mixture thereof.
 3. The process according to claim 1, wherein the reaction is carried out at a temperature of 0° to 150° C.
 4. The process according to claim 1, wherein the reaction is carried out under an atmospheric or elevated pressure.
 5. The process according to claim 1, wherein the reaction is carried out for a period of 10 minutes to 48 hours. 